It is known that hydrophobic films are formed by baking an organopolysiloxane having a silicon-bonded hydrogen atom on the surfaces of various types of substrate requiring water repellency.
For example, Japanese Unexamined Patent Application Publication No. 2000-119642 discloses a water repellent composition for forming a film that includes organopolysiloxane having a silicon-bonded hydrogen atom, and Japanese Unexamined Patent Application Publication No. 2010-060162 discloses a heat pump type air conditioner having a heat exchanger provided with cooling fins having a water repellant film composed of such a composition.